Longwings
Longwings
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A typical wing spread for members of the longwing clade.
Range: Found across the Northern hemisphere at coasts and out at sea, and to a lesser extent further South.
Descended from: Sea quails
Ancestor of: Future unwritten
Longwings are characterised by their ability to glide near indefinitely. They are capable of carrying out all essential functions without landing, with the exception of egg-laying and chick-rearing, which must be done on land.
Most species don't typically live on the wing for more than a few hours at a time if they have the stability of a safe rest spot to choose from, but larger, later species with record wing spans can do out of preference for years at a time if they don't have chicks in that space of time. Such birds evolved a locking mechanism that makes having the wings extended out straight as energy consuming as resting, with the only actual work being the slight muscle contractions to change their heading or stabilise themselves against turbulence, or to gain altitude if there is a lack of any thermal updrafts to send them upwards.
Diet varies between species but it generally incorporates fish and other pelagic sea life such as squid and jellyfish. Most also opportunistically feed on carcasses though larger species might pass up an opportunity at the slightest suspicion of dangerous competition. They can fumble a take-off in a panic and take-off slower than many other birds, so they might prefer the safety of the air to food guarded by a bigger scavenger.
What is true for even some pre-longwing seaquails is especially true for longwings: They are comparatively genetically homogenous across the Northern hemisphere compared to many other tetrapod species, even other birds. This is largely owing to the fact that individual birds can easily circumnavigate the globe in their lifetime in many cases more than once, keeping the genetics fairly mixed. Other factors become stronger in dividing populations into separately breeding species, such as temperature tolerance (and in turn latitude), nesting spot preference or food preference.
Longwings tend to be on the larger side (slightly larger than herring gulls on average). A larger heavier body more strongly resists wind forces when trying to control themselves in turbulence, and a larger body can store more water and fat for long migrations. A larger body also generates more heat and retains that heat for more time, preventing them from becoming too cool in cold conditions when they're high up but not using much muscle power (they also have good feather insulation, with multiple layers of feathers for different purposes).
The hole between the nostrils in the beak allows water to run out more freely. But in addition to this the moist soft tissue on the inner rim is sensitive to temperature, humidity and sensation in air currents more than other exposed parts of the skin. One function of the sensitive tissue around and in the nostrils is that it gives them better perception of their own cutting path through the air when wind and pressure might be unpredictable, making them more informed of their next adjustment. The other is that it makes them hyper aware of weather changes, in particular if a change is likely to indicate oncoming bad weather.
Sinuses in the skull cavities surrounding the nostrils also detect pressure changes over a large range, adding to their abilities to sense very large drops or gains in pressure.
Some species will land any time the weather takes a foul turn, but some larger species can weather some storms and will only make an emergency landing if all the factors add up to one enormous red flag. Even then, some older, more experienced birds (and occasionally younger, more unaware and blundering birds) learn to feel safer braving the air than the ground during the likes of a hurricane, which can carry it's own hazards.
Not true of all longwings but still quite characteristic to the group is the occasional light ornamentation and colouration of the part of the beak that connects what's in front of the nostril opening to the forehead. This is a sexually selected feature. The need for good manoeuvrability and efficiency in the air seems to keep this ornamentation modest in size and air resistance, so brighter colour and contrast in pigmentation become greater relied on. The ornamentation is made of beak material and is not comprised of bone, though some of the bone of the nose bridge is thickened to seat the upper part of the beak.
Tail trails are not universal across all longwings but rather belong to a smaller group within longwings. For those that have them tail trails are a sexually selected trait, with hypnotising rippling wave movements being an essential requirement for the display which is underwhelming without it. But during flight it also provides some extra sensory assistance, allowing them to make finer adjustments in response to currents and turbulence.
Although their population is generally high globally it's also sparse. A few slightly gregarious species exist, but the clade consists mostly of solitary birds that may group up very occasionally but for the most part reject long-term, continuous company. But this doesn't make them unsocial birds. They use updrafts and circling to signal to others a food source that is beyond large enough to share, as this brings opportunities to mingle. Find out who's new in the area, establish order with rivals, and find a mating partner for the upcoming year. Some species keep preference and loyalty to the same partner year after year provided they both survive (remembering and returning to the place they first met to find each other again), and individuals vary within species too, with some being more monogamous, some less so.
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